Load Balancing and Layer 4-7 SwitchingServer Load Balancing and its Benefits
Server load balancing is the process of distributing service requests across a group of servers. This addresses several requirements that are becoming increasingly important in networks:
- Increased scalability
- High performance
- High availability and disaster recovery
Many content-intensive applications have scaled beyond the point where a single server can provide adequate processing power. It is importan to have the flexibility to deploy additional servers quickly and transparently to end-users. Server load balancing makes multiple servers appear as a single server – a single virtual service – by transparently distributing user requests among the servers.
The highest performance is achieved when the processing power of servers is used intelligently. Our advanced server load-balancing infrastructure can direct end-user service requests to the servers that are least busy and therefore capable of providing the fastest response time.
The third benefit of server load balancing is its ability to improve application availability. If an application or server fails, load balancing can automatically redistribute end-user service requests to other servers within a server cluster or to servers in another location. Server load balancing also prevents planned outages for software or hardware maintenance from disrupting service to end-users.
Distributed server load-balancing products can also provide disaster recovery services by redirecting service requests to a backup location when a catastrophic failure disables the primary site.
Layer 4-7 Switching
Layer 4-7 switching refers to 'content or application aware' intelligent switching and deep packet inspection of IP application traffic. By increasing performance, security, availability, and scalability through content-aware intelligence, Layer 4-7 switching has become an indispensable component of new data center and network infrastructures.
What do you gain from Layer 4-7 Switching?
- The ability to make switching decisions based on awareness of users and content enables Layer 4-7 switches to support a number of advanced services, such as:
- Application-intelligent load balancing across application servers, firewalls, and many other devices-based on sophisticated load-balancing algorithms, content, and policies; continuous health-checking; support for backup and overflow devices; and active-active redundant switch configurations - to ensure that requests are efficiently sent to and served by the most appropriate network device.
- Application-intelligent application redirection, based on full Layer 7 inspection of URLs, cookies, and host headers across multiple requests and responses, applied against powerful filtering rules.
- 'Cookie-aware' differentiated services, such as special treatment for frequent shoppers versus casual browsers—plus differentiated bandwidth and jitter characteristics for different types of applications based on awareness of the requested URL, not just on IP address or application port.
- Virtual hosting, by enabling a single public IP address to represent multiple domains, and automatically redirecting requests to the appropriate server or server farm.
- Persistent connections to improve session performance for eBusiness transactions (shopping carts and multi-page forms, for example), Multimedia applications (VoIP, SIP, etc.) and wireless applications.
- Application-aware security that protects servers and applications against attacks ( Virus, Worms, DoS, etc.) and unwanted intrusion while providing continuous service for legitimate traffic.
- Intelligent bandwidth management capabilities that can meter, control and account for resource utilisation by any Layer 2-7 attribute, including application type, client, server farm, filters, service, user class, URL, cookies and content type.